But there were differing accounts on Saturday regarding the death tolls and the perpetrators of the attack.

Two officials said a Pakistani army helicopter had been responsible for the attack in South Waziristan where troops have been battling al-Qaida and allied fighters for days.

But Brigadier Mahmood Shah, chief of security in Pakistan's tribal areas on the border with Afghanistan, blamed armed fighters.

He said five men, five women and three children had been killed when their two vehicles were fired on by armed fighters inside an army cordon around remote villages where troops have been battling foreign fighters and Pakistani allies since Tuesday.

Seven people had been wounded, Shah said.

But a local security official on the border said 12 people including women and children had been killed by an army helicopter on Saturday afternoon.

Pakistani officials blame armed
fighters for the bloodshed

Army denial

"After the army received casualties the gunship helicopters were directed to hit the cars," said the official, who declined to be identified.

An army spokesman denied that civilians had been killed but said some people had been killed in an army attack early on Saturday when trying to escape through the army cordon. He said he did not know how many casualties there had been.

"A number of people were killed there but they were those who were trying to escape," said Major-General Shaukat Sultan.

"No innocent people have been killed."

Troops backed by helicopter gun ships have been fighting several hundred fighters holed up in well-fortified, mud-walled compounds. Officials had thought senior al-Qaida leaders might have been among the militants but that has not been confirmed.

Dozens of people have been killed in the fighting.

Last month tension rose sharply in the largely autonomous and lawless region after troops opened fire on a van killing 11 people.